Studies On The Interaction Mechanism Of Source-sink Relationships In Two-line Hybrid Rice

Abstract The studies were conducted in early rice and late rice. Three two條ine hybrid rice combinations (ZaoS/Tll3~ XuXuan S/T113 and 810S/T113) were used in the study of early rice. Three two條ine hybrid rice combinations (Lu 18S/1l25~. PeiLiangyou 1125 and Zhu 15/1125) and their restoring line 1125 were used in the study of late rice. Several aspects were studied. They are: 1)The characteristics of dry梞atter production and distribution during the filling stage; 2)The characteristics of dry梞atter transport of both the whole production and a single stem; 3) The dynamic changes of grain梖illing and the activities of roots; 4) The area & volume and the physiological activities of source梖low梥ink. The corresponding cultivation measures which coordinated the relationships of source梥ink were also suggested. The main results are as follows: l.The grain plumpness and seed setting rate are very poor in both early and late rice. Late rice is worse than early rice. The difference between empty梘rain rate and unfilled梘rain rate is small in early rice. The poorer seed setting rate mainly results from higher empty梘rain rate in late rice. The main reasons are: Cl) The affinity of intersubspecific hybrid rice combinations is poor; ~ The period of grain梖illing is very late and the grains losed their activities in the early stage. 2.The characteristics of dry梞atter transport were analysed. Results indicated that the dry梞atter transport ratio is very low. Much usable carbohydrate (soluble sugar + starch) remains in the stem (sheath) and the grain plumpness is poor. The main reasons are: ?The impediment of transfusion tissue; ~ The low physiological activities of grains. Grain filling rate reflects the capability of photo梐ssimilation and transport, so it can be used as an index of high yield varieties. 3.The weight of a single stem (sheath) is correlated significantly with the number of larger vascular bundle, the area of vascular bundles and the area of phloem for vascular bundles. Therefore strengthening individual is important in production. The number of large vascular bundle and small vascular bundle-. the area of a large vascular bundle and a phloem are correlated with the number of primary rachis branches and secondary lateral branches of a panic1e~ the number of grains of a panicle. These demonstrate: The anatomic characteristics of transfusion tissue have great effects on the structure of panicle and grain. The weight of a panicle increased during grain filling period is correlated significantly with the mount of dry matter transport through unit area of vascular bundle or phloem in early rice. But the correlation coefficients weren?t significant in late rice. 4.The physiological activities of source梥ink梖low can be reflected through the activities of sucrose梡hosphate synthase (SPS) in leaves~ the activities of catalase in grains and upmost internode in some respects. The activities of sucrose梡hosphate synthase (SPS) in leaves declined gradually during grain filling period. The activities of catalase inupmost internode and grains declined gradually in some combinations, whereas increased again in the middle of grain filling period in some combinations. These coincided with the tendency of grain filling. 5. The phenomenon of premature senescence in roots existed in all combinations (varieties).Thus to improve postphase nutriment of plants~ to prelong the...